Hardness pencil

La description

Hardness of gem correlates closely to the wear resistance; it is most important factor of the value of gem. There are two ways to test the hardness: indirect-vision method and direct test method.

I. Indirect-vision method.

 The hardness of the gem has something to do with how smooth the surface is and how sharp the corners are. So under the gem loupe, we can see clearly how smooth, how plane and how sharp the gem with different hardness is.

II. Direct test method

This method requires a contact between the testing gem and the standard hardness of minerals. In ***2, Germanic mineralogist named Mose put forward ten mineral、talc*1、gypsum*2、calcite*3、fluorite*4、qpatite*5、orthoclase*6、quartz*7、topaz*8、corundum*9、diamond**0，which represent ten standard hardness. The biggest gap is between corundum and diamond.

The hardness pencil : qpatite*5、orthoclase*6、quartz*7、topaz*8、corundum*9 those minerals are mounted in five metal pole respectively, use the corner of those mineral to scratch the gem, you will get the hardness according to the nick you scratch. if there is a nick after you scratched, the sample’s hardness is lower than the standard hardness pencil, if there is no nick after you scratched, that means the sample’s hardness is higher than the standard hardness pencil. 

III: Matters need attention

1.      Use the indirect-vision method to estimate the hardness of the sample;

2.      Find a inconspicuous place, use the talc*1or plaster*2 to scratch the sample, if can’t do, that means the sample’s hardness is higher than the standard hardness pencil, so please use the higher pencil to scratch, repetitive operation, if there is a shadow nick, that means the sample’s hardness is almost the same with the standard hardness pencil, then use the higher hardness pencil to scratch the gem, if there is a deep nick, the sample’s hardness is lower than the standard hardness pencil. so by this way, can get the hardness of gem or the scope of the hardness.

3.      When you scratch, don’t too heave or too light, just the proper vigor

4.      Direct test method cost damage to the gem, so please use it proper. Generally speaking, we won’t use the method to the finished gem.